HVAC523
Soldering
Soldering Copper Tubing

The Common method of joining copper
tubing in hydronic heating systems is
soft soldering using a 95/5 (95 % tin/5
% antimony) solder.

The maximum working pressure rating
for of 95/5 solder is approximately
300psi.
95/5 solder
The alloy content of all solders are listed in this area
95/5 melting range

The melting temperature range for 95/5
solder is 452 – 464 degrees F.

The narrow melting temperature range of
95/5 also means the joint will solidify very
quickly when heat is removed.

In other words, a fine balance of heating
is needed when soldering.
Proper Soldering Procedure

Proper soldering results in clean, neat
and water tight joints.

Sloppy joints, even if water tight,
indicate poor craftsmanship.

With little practice, making good solder
joints will become second nature.
Soldering: step by step
procedure

Step 1. Be sure the tube is cut square,
use a wheel cutter. Avoid using a hack
saw whenever possible.

Step 2. To remove any burrs, ream the
end of the tube with the blade of the
cutter wheel, rounded file or other type of
de-burring tool
Wheel cutter
De-burring tool
Soldering: step by step
procedure

Step 3. Assemble the joint and check it
for proper fit and alignment.



In most cases there will be no problem with
the fit.
However, sometimes a fitting may be
damaged or defective.
If the fitting wobbles noticeably on the pipe,
it should be replaced.
Soldering: step by step
procedure

Step 4. Clean the socket of the fitting
with a properly sized fitting brush.


Be sure to remove any pieces of the steel
brush bristles remaining in the fitting after
cleaning.
These small pieces of steel can create
galvanic corrosion that could eventually
cause a leak in the fitting.
Soldering: step by step
procedure

When cleaning a large amount of fittings,
a cleaning brush can be adapted to fit in
the chuck of a cordless drill.
Cleaning brushes
Hand cleaning brush
Cleaning brush adapted to fit in a drill
Soldering: step by step
procedure

Step 5. Clean the outside of the pipe
with emery cloth.


All oxidation, scale, dirt or paint should be
removed from the tubing surface at least ½”
inch further back than the edge of the fitting
socket.
The tube should appear bright following
cleaning. Be sure to clean all the way around
the perimeter of the pipe.
Cleaning copper pipe
Soldering: step by step
procedure

Step 6. Apply paste flux to the fitting
socket and the portion of the pipe that
fits inside the socket.



The flux chemically cleans the surface of the
copper and helps prevent oxidation of the
surfaces when heat is applied.
Always use a flux brush, not your fingers, to
apply the flux.
Do not apply excessive amounts of flux.
Only a thin film is needed.
Soldering: step by step
procedure

After fluxing, slide the tube into the fitting and,
whenever possible, rotate the fitting once or
twice to further spread the flux.

Finally, wipe the excessive flux off with a
clean rag prior to applying heat.
Applying flux to the fitting and
pipe
Soldering: step by step
procedure

Step 7. Apply heat to the outside of the
fitting socket using a torch.

Keep the blue tip of the flame just above the
surface of the socket.

Move the tip of the torch around the fitting to
promote even heating.
Applying heat to a fitting
Soldering: step by step
procedure

Heating times differ considerably with the
type of torch and gas being used, as well
as the pipe size, ambient temperature
and type of solder.


When the flux begins to sizzle or turn very
clear, test the joint by applying the tip of the
solder to the edge of the joint.
.
Soldering: step by step
procedure

If it sticks but does not melt apply more
heat.

If the solder immediately melts, the joint is
ready to draw in the molten solder by
capillary action
Soldering: step by step
procedure

Once the solder begins to flow, it can be
continually fed into the joint. Only a small
amount of solder is needed.

An experienced pipe fitter knows by sight
how much solder to feed into a joint.

An inexperienced person often feeds
excessive solder into the joint.
Soldering: step by step
procedure

The excessive solder can solidify into small
loose particles inside the pipe.

These can be carried around the system by
the fast moving fluid and become lodged in
valves or circulators.

A good rule of thumb is to use an
approximate length of solder that is equal to
the diameter of the pipe.
Soldering: step by step
procedure

Step 8. After the solder is applied,
remove the torch and if necessary,
carefully wipe the perimeter of the joint
with a clean cloth to remove any excess
solder or flux.

The joint should be allowed be allowed to
cool naturally before being handled or
stressed.
Soldering: step by step
procedure

After the joint has cooled, one last wipe of
the pipe with a damp rag will remove any
remaining flux

This is an important step because flux
residue left on the joint eventually causes
unsightly surface oxidation.
Soldering: step by step
procedure

Be a professional and always
clean every joint
Additional Soldering Tips

Its best to make up piping assemblies on
a horizontal working surface.


The solder flow is more controllable
When soldering has to take place next to
combustible material, place a
noncombustible material, such as sheet
metal, between the torch and the material
you are protecting.
Additional Soldering Tips

Measure all tubing carefully before
cutting.

Allow for the amount of pipe that fill fit
into the fitting socket.
Additional Soldering Tips

Whenever possible, attempt to keep all
piping plumb. (Vertically and horizontally)

Install temporary piping support if
necessary to hold the pipe in proper
alignment for soldering.
Additional Soldering Tips

When soldering valves, open the valve to
allow for the heat to dissipate out of the
valve as to not damage it.

This is especially true for zone valves.
Always read the installation instructions
from the manufacturer of the valve.
Additional Soldering Tips

On fittings that have both soldered and
threaded fittings, make up the soldered
joint first.

This prevents discoloration or burning of
Teflon tape or joint compound during
soldering
Additional Soldering Tips

Always keep one end of the pipe open
when soldering.

If this is not done, pressure can build up
in the pipe due the heat and cause
pinholes to form in the solder.
Additional Soldering Tips

Finally, take a few extra minutes to
clean up excessive flux and solder.

Your customers will notice it!